Comparison of changes in the transverse dental axis between patients with skeletal Class III malocclusion and facial asymmetry treated by orthognathic surgery with and without presurgical orthodontic treatment

Establishment of the mid-sagittal reference plane for three-dimensional assessment of facial asymmetry: a systematic review : Establishment of the mid-sagittal reference plane: a systematic review

OBJECTIVE

To systematically review the literature for mid-sagittal plane establishment approaches to identify the most effective method for constructing the mid-sagittal plane for the evaluation of facial asymmetry.

MATERIALS AND METHODS

Six electronic databases (PubMed, Medline (via Ovid), EMBASE (via Ovid), Cochrane Library, Web of Science, and Scopus) and grey literature were searched for the studies that computed the mid-sagittal reference plane three-dimensionally, using a combination of MeSH terms and keywords. The methodological quality and the level of evidence for the included studies were analyzed using QUADAS-2 and GRADE, respectively.

RESULTS

The preliminary search yielded 6746 records, of which 42 articles that met the predefined inclusion criteria were included in the final analysis. All the included articles reported the construction of the mid-sagittal reference plane (MSP) using varied methods. The risk of bias and concerns regarding the applicability of the included studies were judged to be 'low'. The level of evidence was determined to be 'low' for the effectiveness of the technique and 'moderate' for the ease of clinical applicability.

CONCLUSION

Despite methodological heterogeneity, this review substantiates the comparable efficacy of cephalometric and morphometric MSP construction methods. A fully automated morphometric MSP holds promise as a viable option for routine clinical use. Nevertheless, future prospective studies with an emphasis on the impact, accuracy, and clinical applicability of MSP construction techniques in cases of facial asymmetry are required.

CLINICAL RELEVANCE

The present review will assist clinicians in selecting the most suitable method for MSP construction, leading to improved treatment planning and ultimately more favorable treatment outcomes.

Surgery-First Orthognathic Approach for Correction of Dentofacial Deformity in Unilateral Cleft Lip and Palate

BACKGROUND

Although several studies have reported the advantages of the surgery-first approach for orthognathic correction of class III deformity, there is no report of the success of this approach for patients with cleft lip and palate. Therefore, the purpose of this study was to evaluate the stability and outcome of bimaxillary surgery for cleft-related dentofacial deformity using a surgery-first approach.

METHODS

Forty-one patients with unilateral cleft lip and palate who consecutively underwent Le Fort I and bilateral sagittal split osteotomies for skeletal class III deformity were included. Cone-beam computed tomographic scans before surgery, 1 week after surgery, and after orthodontic treatment were used to measure the surgical and postsurgical changes in jaw position by landmarks, and outcomes of jaw protrusion and relation, incisor angle and occlusion, and menton deviation after treatment. Self-report questionnaires regarding satisfaction with overall appearance of the face and seven facial regions were administered after treatment.

RESULTS

A clinically insignificant relapse was found in the maxilla (<1 mm) and mandible (<2 mm). There was a significant improvement in the jaw protrusion and relation, incisor angle and occlusion, and menton deviation. Responses from the self-report questionnaires completed after treatment indicated that patient satisfaction was high.

CONCLUSION

These findings demonstrate surgical-orthodontic treatment with a surgery-first approach can successfully improve cleft-related dentofacial deformity in patients with unilateral cleft lip and palate.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Three-dimensional evaluation of skeletal stability after surgery-first bimaxillary surgery for class III asymmetry in 70 consecutive patients

Background/purpose

Skeletal stability after orthognathic surgery is essential for positive treatment outcome. This study evaluated the stability of osteotomy segments after surgery-first bimaxillary surgery for class III asymmetry.

Materials and methods

Seventy adults with class III asymmetry consecutively corrected through surgery-first Le Fort I and bilateral sagittal split osteotomies were investigated. Cone-beam computed tomography before treatment (T0), 1-week after surgery (T1), and after all treatment (T2, ≥1-year after surgery) was used to assess surgical movement (T0 to T1) and skeletal stability (T1 to T2) regarding the translation and rotation of the maxillary, mandibular distal, and proximal segments.

Results

At T1, the maxillary segment had moved forward and upward, turned to the deviated side, and rotated downward (all P < 0.01). The distal segment of mandible had moved forward and upward and rotated upward (all P < 0.001). The deviated proximal segment had moved upward, tilted to the opposite side, and rotated upward (all P < 0.001). The opposite proximal segment had moved upward and tilted to the deviated side (both P < 0.01). At T2, significant relapse occurred in the mandible. The distal segment moved forward and upward and rotated upward (all P < 0.001). The deviated proximal segment moved upward, tilted to the opposite side, and rotated upward (all P < 0.001). The opposite proximal segment moved upward and tilted to the deviated side (both P < 0.01).

Conclusion

Clinically significant relapse of class III asymmetry was discovered on the mandibular distal and opposite proximal segments.

Skeletal stability after bimaxillary surgery with surgery-first approach for class III asymmetry is not related to virtual surgical occlusal contact

OBJECTIVES

Surgery-first orthognathic surgery is rarely used in class III asymmetry due to concerns of reduced skeletal stability from unstable surgical occlusion. This study aimed to evaluate if skeletal stability after surgery-first orthognathic surgery is related to virtual surgical occlusal contact or surgical change.

MATERIALS AND METHODS

We studied 58 adults with class III asymmetry, consecutively corrected by Le Fort I osteotomy and bilateral sagittal split osteotomy using a surgery-first approach. Dental casts were manually set to measure virtual surgical occlusal contact including contact distribution, contact number, and contact area. Cone-beam computed tomography taken before treatment, 1-week post-surgery, and after treatment was used to measure surgical change and post-surgical stability of the maxilla and mandible in translation (left/right, posterior/anterior, superior/inferior) and rotation (pitch, roll, yaw). The relationship between skeletal stability and surgical occlusal contact or surgical change was evaluated with correlation analysis.

RESULTS

Significant instability was found in the mandible but not in the maxilla. No correlation was found between the maxillary or mandibular stability and surgical occlusal contact (all p > 0.01). However, a significant correlation was found between the maxillary (roll and yaw) or mandibular (shift, roll and pitch) stability and its surgical change (all p < 0.001).

CONCLUSIONS

In correction of class III asymmetry with surgery-first bimaxillary surgery, the skeletal stability is not related to the virtual surgical occlusal contact, but surgical skeletal change.

CLINICAL RELEVANCE

Planned over-correction is a reasonable option for correction of severe shift or roll mandibular asymmetry in bimaxillary surgery for class III deformity.

[Diagnostic and treatment alternatives for the correction of facial asymmetries: a literature review]

Facial symmetry refers to a complete coincidence of each facial component on the sagittal plane, while asymmetry refers to the bilateral difference between these components. The presence of perfect bilateral symmetry is almost never present in human, so it is more common for individuals to predominate facial asymmetry. However, this condition can result from functional and esthetic problems. This research seeks to determine the alternatives, diagnosis and ideal treatment plan for the correction of each type of facial asymmetry through orthognathic surgery. For this purpose, a review of articles published between 2015 to date was carried out. Selecting those that were focused on describing or evaluating facial and dentofacial symmetry and asymmetry, type of diagnosis or treatment plan, including clinical cases. The Google search engine, SciELO and databases of medical interest, such as PubMed, PMC and Medigraphic were used. According to the research and treatments carried out during the last few years in the dental clinic, it has been proven that orthognathic treatment accompanied by previous planning is the best option for the management of skeletal facial asymmetries.

Ramal inclination in the frontal plane after bimaxillary orthognathic surgery in skeletal class III facial asymmetry : Spontaneous changes and stability

PURPOSE

This study aimed to observe spontaneous changes of ramal inclination in the frontal plane (FRI) and its stability in skeletal class III asymmetry patients corrected with bimaxillary surgery. The correlation between FRI change and surgical skeletal change was also investigated.

METHODS

Forty-nine patients with skeletal class III facial asymmetry who underwent orthognathic surgery with at least 1° change in FRI after surgery were analyzed. FRI and other factors were measured on frontal and lateral cephalograms before surgery (T1), after surgery (T2), and at follow-up after at least 6 months (T3). Correlation analysis was performed to determine pre- and postoperative factors associated with FRI change and stability.

RESULTS

FRI increased significantly on the deviated side and decreased on the nondeviated side after surgery. The FRI changes remained stable during follow-up. No correlation between FRI changes and skeletal changes during surgery were found except between the change of FRI during follow-up (T3-T2) and mandibular setback amount (T2-T1), with a weak coefficient of 0.32.

CONCLUSION

The FRI changes after bimaxillary orthognathic surgery in skeletal class III asymmetry reduced the FRI difference between the deviated and nondeviated side and remained stable for at least 6 months after surgery. No clinically significant correlation was found between measured skeletal changes during surgery and FRI changes.

Type of mandibular asymmetry affects changes and outcomes of bimaxillary surgery for class III asymmetry

OBJECTIVES

Various methods have been used to classify class III asymmetry. There is little information on the use of an asymmetry index to examine soft tissue changes and outcomes for patients with class III asymmetry. This study aimed to (1) evaluate soft tissue changes and outcomes for three types of mandibular asymmetry and (2) determine if measures are associated with type of asymmetry.

MATERIALS AND METHODS

Adults who consecutively underwent bimaxillary surgery using surgery-first approach for correction of class III asymmetry were divided into three groups based on type of mandibular asymmetry. This previously reported classification system is simple and mutually independent, categorizing mandibular asymmetry according to the amount and direction of ramus asymmetry relative to menton deviation: patients with a larger transverse ramus distance on the menton deviation side were divided into group 1 and group 2; group 1 (n = 45) exhibited a menton deviation larger than ramus discrepancy; group 2 (n = 11) exhibited a menton deviation less than ramus discrepancy; group 3 (n = 22) had larger transverse ramus distance contralateral to the side of the menton deviation. Soft tissue facial asymmetry indices, calculated from cone beam computed tomography images, assessed midline and contour asymmetry presurgery, changes postsurgery, and outcomes.

RESULTS

Compared with groups 1 and 2, the presurgery index for contour and midline asymmetry was smallest for group 3. All the three groups had significant improvement in midline asymmetry postsurgery, and outcome measures were good; there were no differences between groups. However, contour asymmetry only improved significantly for groups 1 and 2. The outcome for contour asymmetry was fair for groups 1 and 3 and poor for group 2.

CONCLUSIONS

Bimaxillary surgery significantly improved facial midline asymmetry. The type of mandibular asymmetry was associated with postsurgical changes and outcomes for contour asymmetry.

CLINICAL RELEVANCE

Understanding the types of mandibular asymmetry could help clinicians to develop treatment plans and predict treatment changes and outcomes.

Three-dimensional evaluation of dental decompensation and mandibular symphysis remodeling on orthodontic-surgical treatment of Class III malocclusion

INTRODUCTION

The purposes of this research were to identify the buccolingual inclinations of the mandibular teeth and the mandibular symphysis remodeling that result from the orthodontic decompensation movement.

METHODS

The sample consisted of 30 adults with Class III dentofacial deformity, who had presurgical orthodontic treatment. Three-dimensional images were generated by cone-beam computed tomography scans at 2 different times (initial and before orthognathic surgery). Three-dimensional virtual models were obtained and superimposed using automated voxel-based registration at the mandible to evaluate B-point displacement, mandibular molar and incisor decompensation movement, and symphysis inclination and thickness. The 3-dimensional displacements of landmarks at the symphysis were quantified and visualized with color-coded maps using 3D Slicer (version 4.0; www.slicer.org) software.

RESULTS

The measurements showed high reproducibility. The patients presented mandibular incisor proclination, which was consistent with the movement of tooth decompensation caused by the presurgical orthodontic treatment. Statistically significant correlations were found between the inclination of the mandibular incisors, symphysis inclination, and B-point displacement. Regarding the thickness of the symphysis and the inclination of the incisors, no statistically significant correlation was found.

CONCLUSIONS

The buccolingual orthodontic movement of the mandibular incisors with presurgical leveling is correlated with the inclination of the mandibular symphysis and repositioning of the B-point but not correlated to the thickness of the symphysis.

Comparison of Changes in the Condylar Volume and Morphology in Skeletal Class III Deformities Undergoing Orthognathic Surgery Using a Customized versus Conventional Miniplate: A Retrospective Analysis

With the great leap in the development of three-dimensional computer-assisted surgical technology, surgeons can use a variety of assistive methods to achieve better results and evaluate surgical outcomes in detail. This retrospective study aimed to evaluate the postoperative stability after bilateral sagittal split ramus osteotomy by volume rendering methods and to evaluate how postoperative stability differs depending on the type of surgical plate. Of the patients who underwent BSSRO, ten patients in each group (non-customized miniplate and customized miniplate) who met the inclusion criteria were selected. Preoperative and postoperative cone-beam computed tomography data were collected, and condylar morphological and landmark measurements were obtained using Checkpoint and OnDemand software, respectively. The postoperative condylar morphological dataset revealed no significant difference (p > 0.05) between the two groups. No significant difference (p > 0.05) was observed between the two groups in horizontal, vertical, or angular landmark measurements used to quantify operational stability. These results indicate that there is no difference in the surgical outcome between the patient-specific system and the conventional method, which will allow clinicians to take advantage of the patient-specific system for this surgical procedure, with favorable results, as with the conventional method.

Three-dimensional evaluation of skeletal and dental changes in patients with skeletal class III malocclusion and facial asymmetry after surgical-orthodontic treatment

OBJECTIVE

To evaluate skeletal and dental changes in patients with skeletal Class III malocclusion and facial asymmetry after surgical-orthodontic treatment using cone-beam computerized tomography (CBCT).

METHODS

This study included forty adult patients diagnosed with skeletal Class III malocclusion and asymmetry who underwent either isolated mandibular surgery or bimaxillary surgery. CBCT scans were taken before treatment (T0), at the completion of presurgical orthodontic treatment (T1) and after treatment (T2). Mimics 17.0 and 3-Matics 7.0 were used to measure skeletal and dental parameters. Skeletal and dental changes within each group from pretreatment to posttreatment were assessed, and Pearson correlation analysis was used to analyze the correlations among skeletal changes.

RESULTS

The three-dimensional changes in condylar position were insignificant after surgical-orthodontic treatment in either group (P > 0.05). However, in the one-jaw surgery group, there were significant backward rotations of the condyle and ramus on the nondeviated side (P < 0.05), and the condyle on the deviated side rotated inward and forward significantly in the two-jaw surgery group (P < 0.05) at T2. There were no significant differences in the changes in the total alveolar bone thickness of bilateral first molars during dental decompensation (P > 0.05). The ratio between the buccal and the total bone thickness around the maxillary first molar on the deviated side decreased significantly at T1, as did those around the mandibular first molar on the nondeviated side (P < 0.05).

CONCLUSIONS

Condylar angulations were less stable after treatment (7 to 9 months after surgery) in both the one-jaw and the two-jaw surgery groups, while condylar displacements were insignificant. In addition, orthodontists should keep a watchful eye to the relative position of the root in the alveolar bone during tooth decompensation.

Facial asymmetry correction: From conventional orthognathic treatment to surgery-first approach

The surgery-first approach (SFA), which proceeds without presurgical orthodontic treatment, is assumed to shorten the treatment course because the direction of post-surgical orthodontic tooth movement conforms to the normal muscular forces. Moreover, the regional acceleratory phenomenon (RAP), evoked by surgery, helps in tooth alignment and compensation in a faster way. Although SFA has definite advantages, especially in class III individuals, there is a lack of data about its indications in patients with facial asymmetry. In this article, we reviewed recently published articles on the treatment of asymmetric patients using the SFA. Different aspects, including the three-dimensional assessment of stability in different planes, approaches for fabrication of a surgical splint, predictability of the results, skills needed for bimaxillary surgery, indications as the treatment of choice for condylar hyperplasia, and combination with distraction osteogenesis in candidates with severe asymmetries were found to be the main topics discussed for patients presenting with facial asymmetry

Virtual Orthodontic Surgical Planning to Improve the Accuracy of the Surgery-First Approach: A Prospective Evaluation

PURPOSE

We developed an innovative computer-assisted method to increase the accuracy of the surgery-first (SF) approach by linking the virtual orthodontic planning (VOP) with the virtual surgical planning (VSP).

MATERIALS AND METHODS

Fifteen consecutive patients were enrolled from 2013 to 2015. All 15 patients had initially undergone cone-beam computed tomography (CBCT; 15 × 15 field-of-view) and intraoral digital scanning of the dental arches. The DICOM (Digital Imaging and Communications in Medicine) data set and STL files were processed using the SimPlant O&O platform (Dentsply-Sirona, York, PA), which facilitates skeletal, dental, and soft tissue modeling and subsequent realization of the VOP/VSP. The VSP was reproduced using computer-aided design and computer-aided manufacturing surgical splints, and the VOP was realized via postoperative orthodontic treatment. At the end of treatment, all the patients underwent repeat CBCT and digital scanning of the dental arches, and the new data sets were compared with the original data sets to determine the deviations. To evaluate skeletal accuracy, we assessed all points within an arbitrary range of -2 to +2 mm. To evaluate dental accuracy, the arbitrary range was -0.8 to +0.8 mm.

RESULTS

The average duration of orthodontic treatment was 17.9 months. The accuracy of maxillary treatment averaged 0.0702 ± 2.0724 mm and that of mandibular treatment, 0.2811 ± 1.9993 mm. The average upper and lower dental arch accuracy was -0.0029 ± 1.125 and -0.0147 ± 1.263 mm, respectively. The maxillary surgery accuracy was 75.3% and that of mandibular surgery 74.0%, both within the -2 to +2-mm range. The upper and lower arch accuracy was 58.86 and 51.53%, respectively, both within the -0.8 to +0.8-mm range.

CONCLUSIONS

The use of the VOP/VSP improved the diagnostic and therapeutic SF preoperative planning. VOP contributed significantly in this context. The accuracy of skeletal repositioning was acceptable; however, the VSP should be rendered more reproducibly in the future to minimize the need for orthodontic compensation and to maximize the advantages of SF.